Must Tune?

[emsguy]

happy new year everyone.

I have a 2012 2SS A6 convertible. I am putting on JBA shortie headers, JBA high flow catted midpipes, a Corsa cat back exhaust, and Volant intake.

I know that a tune will give me more power, but that it may also invalidate the powertrain warranty.

so - - - here's the question: what if I put on all of these mods and don't tune? I know I won't get as much power, but will the new mods without a tune screw things up?

as always, all opinions are welcomed but informed, experienced opinions are preferred.

[SUX2BU]

No.

[lakersftbl69]

You will need a tune in order for the engine light to not come on

[Steck]

Putting those parts on voids your warranty anyway.

If you don't tune it, and your MAF calibration is off, the transmission will eat itself. It may happen slow, and it may happen quick. The MAF is used for torque reporting, and if the torque values are inaccurate, the TCM uses the wrong shift properties which can result in a burned up transmission. Manual trans guys don't really have a concern... It just won't run at full potential.

[Cpanthers85]

You will throw a check engine light because of the headers and the high flow cats. It's going to throw the O2 sensors off.

Besides, if a dealer sees your headers, unless they are "cool", they are going to void the warranty.

Even if you put the car back to stock before you take it to the dealer, they will still be able to see in the ECU history that you were running with a CEL and very lean. They will put 2+2 together...

[emsguy]

thank you all for your informed and informative responses. I have read them all, and have tried to understand.

I was reminded by your responses that I am a somewhat of a dinosaur. I got my first drivers' license in 1966. That's right. I have been driving for 45 years. My first car was a '65 Buick Skylark GS convertible with a two-speed automatic transmission. I think it was a power glide. I can remember buying Sunoco 260 for 32.9 cents per gallon. I was educated on cars with manual chokes. I can, and have, synched three SU carbs on a 4.2 E-Type DOHC straight six. Rebuilt a TR-6 frame-up. I understand, and have experienced, the smoke theory of Lucas electrical systems. I understand, and appreciate, mechanical systems. Electrons, however, baffle the heck out of me.

You say that the AT of my 2SS senses the torque the engine is putting out and shifts accordingly. I believe you, but I don't understand. If the transmission truly senses the torque output of the engine directly, then it shouldn't matter whether I add headers, midpipes, and aftermarket exhaust. Any change in the engine torque caused by these mods would be sensed by the transmission and it would adjust accordingly. After all, 300 ft/lbs of torque is 300 ft/lbs of torque regardless of which header is used to produce it, or at what rpm it is produced.

However, if the transmission interpolates the torque figure from a pre-programmed map of stock engine values (at 3,000 rpm, the engine is putting out X ft/lbs of torque and at 3,500 rpm it is putting out Y ft/lbs of torque), then changing the headers, etc. would confuse the transmission. It would be looking for X ft/lbs of torque at 3,000 rpm and the engine was in fact putting out Z ft/lbs of torque.

Have I got it?

Once again, I am not questioning your superior wisdom and experience on this point, just trying to understand it.

Thanks again.

[Steck]

Originally Posted by emsguy

However, if the transmission interpolates the torque figure from a pre-programmed map of stock engine values (at 3,000 rpm, the engine is putting out X ft/lbs of torque and at 3,500 rpm it is putting out Y ft/lbs of torque), then changing the headers, etc. would confuse the transmission. It would be looking for X ft/lbs of torque at 3,000 rpm and the engine was in fact putting out Z ft/lbs of torque.

That's pretty close. The headers won't impact it much. The PCM takes the airflow that it is seeing and says "based on this much air flow and this engine speed and this spark, the engine is making X torque". The reason the MAF calibration is very important is it is the basis of the torque calculation.

[ParisTNDude]

I think you would want one, but the shorty headers won't cause you to throw a code from what I've heard on this forum. I understand lot's of C5 members went the shorty header route instead of the long tubes just to avoid the need for a tune! Long tubes locate the oxygen sensor probably a foot or more further from the exhaust ports and apparently they run cooler there and aren't calibrated for the cooler temperature. My Camaro didn't throw a code when I installed my long tubes and I was surprised.

[emsguy]

Originally Posted by Steck@Craven

That's pretty close. The headers won't impact it much. The PCM takes the airflow that it is seeing and says "based on this much air flow and this engine speed and this spark, the engine is making X torque". The reason the MAF calibration is very important is it is the basis of the torque calculation.

thanks. good information.

how far is your shop from Chicago? from Peoria?

[Rhino79]

The o2 codes come from lack of a catalyst or a high flow catalyst. The secondary o2s are the ones that throw the codes. A lot of long tubes delete the cats as mine did and obviously the codes for the rear o2s have to be disabled to prevent a cel.

[Steck]

Originally Posted by emsguy

thanks. good information.

how far is your shop from Chicago? from Peoria?

About 200 miles from Peoria.

Originally Posted by Rhino79

The o2 codes come from lack of a catalyst or a high flow catalyst. The secondary o2s are the ones that throw the codes. A lot of long tubes delete the cats as mine did and obviously the codes for the rear o2s have to be disabled to prevent a cel.

While true, some headers also result in slow switching of the front O2 sensors.

[emsguy]

Originally Posted by Steck@Craven

About 200 miles from Peoria.


While true, some headers also result in slow switching of the front O2 sensors.

how long does a tune take for you to do? I am truing to figure out if I can drive down from Peoria, have you do the tune, and drive back in a day.

thanks